I always create a "base-session" I call this Daily Operations with a version and date. With the base session, everything I do afterwards is only a matter of changing driver commands and schedules in the Schedule Library along with placing and removing consists as necessary.
This is the basis for others that follow such as "Maintenance Day" which I'm still working for my Gloucester Terminal Electric where the plethora of AI drivers are at the terminal while the ballast and ties train is out on the mainline. Freight switching, however, continues normally. I once had a freight-only session too setup, but I trashed that one in another version when I upgraded the routes.